The present invention relates to a new and improved suture anchor and more specifically to a suture anchor which is capable of expanding in a patient""s body to enable the anchor to withstand relatively large pull-out forces.
Anchors are commonly utilized to retain sutures in a patient""s body. The anchors have previously been formed of metal, such as stainless steel or titanium. In addition, anchors have been formed of biodegradable materials. These known anchors have relied upon mechanical interlocks between the body tissue and the anchor to retain the anchor in place against the influence of forces transmitted through the suture to the anchor. It has previously been suggested to construct anchors in the manner disclosed in U.S. Pat. Nos. 5,405,359; 5,403,348; 5,203,787; 5,046,513; and 5,041,129. In addition, an anchor formed of body tissue is disclosed in co-pending application Ser. No. 08/626,393 filed Mar. 29, 1996 filed by Peter M. Bonutti and entitled xe2x80x9cSuture Anchorxe2x80x9d.
The present invention relates to a new and improved suture anchor which absorbs body liquid. A suture extends from the anchor. The anchor and the suture are inserted into a patient""s body. When the anchor is disposed in the patient""s body, the anchor expands. The anchor expands by absorbing body liquid and/or by its own natural resilience. As the anchor expands, an improved interlock is obtained between the anchor and the body tissue to enable the anchor to resist relatively large tension forces transmitted through the suture.
The anchor may be formed of a material which absorbs body liquid. Alternatively, the anchor may contain cells which are expanded to absorb body liquid.
The anchor may have a leading end portion which forms an opening in an imperforate body surface. Alternatively, the anchor may be inserted into body tissue through an opening formed in the body tissue by a member other than the anchor. The configuration of the anchor may be changed while the anchor is in the body tissue.